The indexOf() method of TypedArray instances returns the first index at which a given element can be found in the typed array, or -1 if it is not present. This method has the same algorithm as Array.prototype.indexOf().

Try it

const uint8 = new Uint8Array([10, 20, 30, 40, 50]);

console.log(uint8.indexOf(50));
// Expected output: 4

// From position 3
console.log(uint8.indexOf(20, 3));
// Expected output: -1

console.log(uint8.indexOf(51));
// Expected output: -1

Syntax

indexOf(searchElement)
indexOf(searchElement, fromIndex)

Parameters

searchElement

Element to locate in the typed array.

fromIndex Optional

Zero-based index at which to start searching, converted to an integer.

Return value

The first index of searchElement in the typed array; -1 if not found.

Description

See Array.prototype.indexOf() for more details. This method is not generic and can only be called on typed array instances.

Examples

Using indexOf()

const uint8 = new Uint8Array([2, 5, 9]);
uint8.indexOf(2); // 0
uint8.indexOf(7); // -1
uint8.indexOf(9, 2); // 2
uint8.indexOf(2, -1); // -1
uint8.indexOf(2, -3); // 0

Specifications

Browser compatibility

See also

• Polyfill of TypedArray.prototype.indexOf in core-js
• JavaScript typed arrays guide
• TypedArray
• TypedArray.prototype.findIndex()
• TypedArray.prototype.findLastIndex()
• TypedArray.prototype.lastIndexOf()
• Array.prototype.indexOf()
• String.prototype.indexOf()